#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int Func(int arr[], int len)
{
	int ret = 0;
	for (int i = 0; i < len; i++)
	{
		ret ^= arr[i];
	}
	return ret;
}
int main()
{
	int arr[] = { 1,2,3,4,5,1,2,3,4 };
	int ret = Func(arr, sizeof(arr) / sizeof(arr[0]));
	printf("%d\n", ret);
	return 0;
}